If a straight line falling on two straight lines make the exterior angle equal to the interior and opposite angle on the same side, or the interior angles on the same side equal to two right angles, the straight lines will be parallel to one another.
SI in duas rectas lineas recta incidens linea externum angulum interno, & opposito, & ad easdem partes, æqualem fecerit; Aut internos, & ad easdem partes duobus rectis æquales: Parallelæ erunt inter se ipsæ rectæ lineæ.